I'm 240-250 and my Z125 with full exhaust, intake, and PCV would cruise between 55-60 depending on head wind. The Z125 tops out at 67 mph with stock gearing. That's rev limiter.

The Grom is a few MPH less than the Z125 for top speed with me on it. I often have to down shift to 3rd on the Grom to keep speeds up. I don't have to do that on the Z125 which is geared a little lower.

The monkey is the same as the grom. It just has slightly taller tires.